Recently, low power consumption is requested for an imaging device in a digital camera etc. Especially for a battery-driven portable imaging device whose power supply is limited, the low power consumption is earnestly requested for the purpose of increasing the number of shot still images, the moving image shooting time, etc. Furthermore, in the shooting scene at a low temperature in skiing, snowboarding, etc., the number of shot images and the shooting time are smaller and shorter than at a normal temperature due to the feature of a battery at a low temperature, thereby further strongly requesting lower power consumption.
The following devices are known as imaging devices for the low power consumption.
For example, there is a camera which automatically reduces the setting of display time limit when a setting change is made from the shooting mode to the communication mode, and minimizes the power consumption of a display device during communications (for example, refer to the following patent document 1). With the camera, the display brightness of the display device is reduced or turned off under a specified condition.
On the other hand, the imaging device may be a digital camera provided with the function of automatically tracking a moving subject while moving images are taken (hereafter referred to as an “automatically tracking function”). Using the function of the automatically tracking function of the digital camera, it is possible to continuously bring a specific subject (for example, a face etc.) into focus. Thus, a user may easily shoot a moving image while continuously bringing a desired moving subject into focus.
The following device is known as an imaging device provided with an automatically tracking function.
For example, known is a safe area warning device applied to a TV camera system having an automatic AF frame tracking function of automatically tracking a desired subject with an AF area (AF frame) as a target range in which focusing is performed in an autofocus (AF) process (for example, refer to the following patent document 2). The device may appropriately attract a camera user not to allow a subject to be shot to travel outside the safe area by tracking the subject using the automatic AF frame tracking function.
Furthermore known is an imaging device which displays a guide for indicating the direction of movement of an object to be shot when the object to be shot which is being tracked travels outside the screen of the display unit (for example, refer to the following patent document 3). The device may easily return the object to be shot, which has deviated from the angle of view for shooting, back within the angle of view for shooting.
Also known is a camera system which detects the deviation of a subject when it deviates from a display screen, raises a warning operation, or captures again a subject by performing a zooming operation in the width direction, or captures the subject again by performing predicting tracking and a scanning operation (for example, refer to the following patent document 4). The system may perform an appropriate process without imposing an excess load on a user when a subject is lost.    [Patent Document 1] Japanese Laid-open Patent Publication No. 11-38494    [Patent Document 2] Japanese Laid-open Patent Publication No. 2010-152135    [Patent Document 3] Japanese Laid-open Patent Publication No. 2007-129480    [Patent Document 4] Japanese Laid-open Patent Publication No. 7-30795